This invention relates to apparatus wherein two sets of paramagnetic members are alternately magnetized to produce bidirectional movement of a driven body. Devices of this broad general type are known as exemplified by the following U.S. Pat. Nos.:
Feldman--3,320,894 PA1 Perron--3,384,021 PA1 Waltrip--3,492,819 PA1 Tukamizawa--3,606,595 PA1 Kurpanek--3,878,412.
This invention is similar in many respects to the apparatus disclosed in U.S. Pat. No. 4,121,139, and is similar to the apparatus of Macy U.S. Pat. No. 3,488,614 in the respect that a plurality of spaced apart paramagnetic bodies are drawn together by magnetic attraction to close the gaps between them. The Macy device, however, is unidirectional and does not provide some energy-conserving features of the present invention.
According to the present invention, the forces of magnetic attraction are used to produce bidirectional movement, such movement being capable of exerting a substantial force over a substantial distance. The ratio of such force to the energy consumed is substantially greater than in a system which relies on both magnetic repulsion and magnetic attraction. The invention in its preferred embodiment is also more energy efficient because the magnets within a given set are energized sequentially rather than simultaneously; and, some of the magnets are deenergized after the adjacent gaps have been closed and before other gaps in the respective set have been closed. In the disclosed embodiment, no more than about 36% of the magnets are energized at any time.
According to the invention, the apparatus for producing movement of a driven body includes two sets of intermediate paramagnetic members which operate respectively to move the driven body in first and second directions. At least one stationary paramagnetic member and at least one driven paramagnetic member are arranged so that each said set has a driven member at one end and a stationary member at its opposite end. The driven member is connected to the driven body, and the intermediate members are movable from mutually proximate relative positions to mutually distant relative positions where they are separated by gaps. Means are provided for limiting the size of the gaps to prevent excessive separation between adjacent members. Energizing means are provided for alternately magnetizing the first set of members and the second set of members to close the gaps by magnetic attraction, thereby moving the driven body alternately in the first direction and the second direction.
Preferably, the driven member is a reciprocating shaft which extends through the members and lies parallel to a common longitudinal axis along which both sets of members are disposed. The members in a set are magnetized sequentially at spaced times and, to conserve energy, at least some of the members in a set are deactivated after their adjacent gaps have been closed and before other gaps in the respective set of members have been closed. A compression spring is located between a pair of the adjacent members for compression when the members are moved to their mutually proximate relative positions by magnetic force, whereby the members are forced apart when the magnets are deenergized. The apparatus is provided with stationary members located at both ends of each set, operable when the first set is magnetized for magnetically attracting the driven magnet of the second set to the stationary magnet adjacent thereto. Similar means operate in a reverse direction for attracting the driven member of the first set to a stationary magnet.
For a further understanding of the invention, reference is hereby made to the accompanying drawings and description of a preferred embodiment.